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At least 19 recordsLinked to original sources
PubMed1976

Effect of psychrotrophic bacteria from raw milk on milk proteins and stability of milk proteins to ultrahigh temperature treatment.

The effects of psychrotroph growth in raw milk on proteins of mils and on the response of milk proteins to heat treatments with ultrahigh temperature were studied. Ten gram-negative psychrotrophs isolated from raw milk readily attacked raw milk proteins. Kappa- and beta-casein were most susceptible although some of the isolates also attacked the whey proteins. Detectable proteolysis did not require large psychrotroph populations. A 10 to 20% decrease in kappa-casein during 2 days at 5 C accompanied growth of one isolate to a population of only 10,000/ml. Growth of psychrotrophs in raw milk predisposed the proteins to deleterious effects of ultrahigh temperature treatments. Ultrahigh temperature treatment by direct steam injection had little effect on raw milk caseins and decreased alpha-lactalbumin and beta-lactoglobulin by 21% and 34%, respectively. Milk that had undergone proteolysis exhibited decreased detectable kappa-, beta-, and alphas-caseins and increased loss of beta-lactoglobulin as a result of ultrahigh temperature treatment. Milk suffering extensive kappa-casein degradation coagulated during ultrahigh temperature treatment. Coagulation during or shortly after heating increased with severity of heat treatment and size of psychrotroph population.

Animals↗
PubMed1975

Concurrent studies of the flow of digesta in the duodenum and of exocrine pancreatic secretion of calves. 3. Further studies on the addition of fat to skim milk and the use of non-milk proteins in milk-substitute diets.

1. The flow of digesta through the duodenum and the concurrent secretion of the pancreas were studied in four Friesian calves given four milk-substitute diets. The diets were: reconstituted, "mildly" pre-heated, spray-dried skim-milk powder with (SKF) or without (SK) margarine fat or with 5o percent of the skim-milk powder in diet SKF replaced by soya-bean flour (ASKF) or fish-protein concentrate (BSKF), together with dried whey. The diets were given ad lib. twice daily from 13 to 37 d of age, each diet being given for 6 consecutive days. Collections of duodenal digesta and pancreatic secretions, from cannulas, were made for 12 h after feeding the 6th and 12th meals ("experimental" meals) for each diet. 2. The diets fed as "experimental" meals contained polyethylene glycol (PEG) as a fluid (whey) marker and goat's milk containing (3H)lysine as a marker for total protein; beta-carotene was added as a lipid marker to the three diets containing margarine fat. 3. Over the 12 h postprandial period, the patterns of duodenal digesta flow and secretion of pancreatic fluid did not differ markedly between the four diets. The abomasal outflow of both nitrogen and lipid in a 12 h postprandial period was related to their intakes from the "penultimate" (5th and 11th) meals for diets SKF and SK BUT TO THEIR INTAKES AT THE "EXPERIMENTAL MEALS" FOR DIETS ASKF and BSKF. Secretion of pancreatic enzyme activity was highest during the 1st hour after feeding but the main outflow from the abomasum of total N and lipid occurred 5-10 h after feeding. 4. The time required for all the whey marker (PEG) to pass through the duodenum was similar for diets SKF and SK, but only 53 and 42 percent respectively of the ingested protein marker passed through the duodenum in the 12 h after feeding. More acid appeared to be secreted by the abomasum when diet SK was given; also less undigested protein passed out of the abomasum after giving this diet. It is concluded that the physical absence of fat globules in the abomasal clot increases the degree of proteolysis. 5. The secretions of pancreatic fluid and pancreatic enzyme activity were all markedly lower for diet SK than for diet SKF. 6. With diets containing non-milk proteins (ASKF and BSKF), abomasal proteolysis was less efficient and the ingested protein passed out of the abomasum more rapidly than for diet SKF. There was no difference in the rate of abomasal outflow of the whey fluids between diets SKF, ASKF and BSKF. 7. In comparison with diet SKF, diets ASKF and BSKF tended to induce less pancreatic enzyme secretion over a 12 h postprandial period, with the exception of lipase. 8. There appeared to be no direct relationship between the quantities of any of the pancreatic enzymes secreted during a postprandial period and either the concurrent flow of duodenal digesta or the total quantities of dietary constituents passing through the duodenum.

Animal Nutritional Physiological Phenomena↗
PubMed1979

Identification, partial purification and biochemical characterization of gamma-glutamyltranspeptidase present as a membrane component in skimmed milk and milk fat-globule membranes, and in mammary-tumour virus from the milk of infected mice.

The enzyme gamma-glutamyltranspeptidase was reproducibly found to be associated with mouse milk particles; it is present in milk fat-globule membranes and mouse mammary-tumour virus of infected Swiss mice, also in particles from the milk of uninfected mice. The enzymatic activities observed range among the highest reported for mammalian tissues. The enzyme was partially purified from mouse mammary-tumour virus, and from milk fat-globule membranes. The molecule requires the presence of detergents to remain soluble, behaves as a high molecular weight component, properties characterizing integral membrane proteins. Kinetics, and the effect of competitors as well as of specific inhibitors show this enzyme to be identical to the well-known kidney gamma-glutamyltranspeptidase ((gamma-glutamyl)-peptide:amino-acid gamma-glutamyltransferase, EC 2.3.2.2). Other oncornaviruses budding from cultured cells originally expressing the enzyme in their plasma membrane also incorporate the enzyme in their structure.

Animals↗
PubMed1977

Mechanism of milk secretion: milk composition in relation to potential difference across the mammary epithelium.

1. In conscious lactating goats a significant correlation was found between blood-milk potential difference (p.d.) and milk [lactose] such that in goats with a lower milk [lactose], milk was more negative with respect to blood.2. When mannose was substituted for glucose in the substrate mixture of isolated perfused goat mammary glands, milk yield and milk [lactose] fell while milk [Na] and [K] increased; in parallel experiments the blood-milk p.d. changed such that milk became more negative with respect to blood. These changes were reversed following the addition of glucose.3. When milk was made hypertonic by the addition of hyperosmotic sucrose or lactose solutions, water entered milk osmotically and milk became electrically less negative or even positive with respect to blood in goats, cows and guinea-pigs.4. No effect on p.d. was apparent following the addition of isosmotic sucrose to milk in goats.5. When milk was held in the teat of goats by a pneumatic cuff around the base of the teat, no effect on p.d. was apparent when hyperosmotic sucrose was introduced into this teat pouch.6. It is suggested that waterflow-induced potentials (the streaming potential and the transport number effect) can be induced across the mammary epithelium.7. In goats exogenous oxytocin lowered milk [lactose] and blood-milk p.d. became less negative with respect to blood.8. In non-lactating and mastitic glands of goats the blood-milk p.d. was within 0.5-2.5 mV of zero.9. The effects of oxytocin, and the low p.d. in non-lactating and mastitic glands, are compatible with the view that in such circumstances there is a paracellular pathway across the mammary epithelium which partially short-circuits the two sides.10. It is suggested that, with water being drawn osmotically into milk to dilute newly formed lactose, waterflow-induced potentials may be responsible for establishing the normal p.d. across the apical membrane of the secretary cell, thereby keeping milk [K] and [Na] lower than in intracellular fluid.

Animals↗
PubMed1977

Iron absorption from human milk, simulated human milk, and proprietary formulas.

Studies from our laboratory have shown that iron is better absorbed from human milk than from cow milk and that human milk can provide insufficient iron for infants during their first year. We compared iron availability from human milk with that from other formulas and determined the factors responsible for its superiority. Adults were fed 100 ml of human milk, simulated human milk, simulated human milk containing added lactoferrin, two commercial formulas containing iron, 12 mg/qt, and human milk that had been boiled. The simulated human milk resembled human milk in concentration of protein, fat, carbohydrate, iron, total minerals, calcium, and phosphorus. Iron 59 was added to each feeding and iron incorporation into RBCs was determined 14 days after each feeding. Percent iron absorption was highest from human milk and lowest from the commercial formulas. The simulated human milk supported a 9.0% absorption; addition of lactoferrin reduced this to 4.7%. Net iron absorption was 0.12 mg/liter from human milk and 0.40 and 0.37 mg/liter from the iron-enriched commercial formulas. Absorption of iron from boiled human milk was the same as from the unboiled milk. This study confirms the unique ability of human milk to promote iron absorption. Simple manipulation of the protein, fat, lactose, calcium, phosphorus, or lactoferrin content of proprietary milk did not reproduce the iron absorption demonstrated with human milk.

Adult↗
PubMed1977

Blood plasma and milk prolactin, and effects of sampling technique on composition of milk from suckled ewes.

Relations of techniques of sampling milk to its composition and concentrations of prolactin in blood plasma and milk from 59 suckled ewes were compared; Prolactin in milk and blood samples 0 to 2 h (hour 0) after removal of lambs did not differ significantly within autumn or summer, but both were doubled in summer. After the hour 0 sampling (summer only), one side of the udder of each of 12 ewes (group 1) was milked hourly for 4 h, and the opposite side was milked only at 0 and 4 h. Group 2 ewes were milked only at 0 and 4 h and blood was collected from both groups at 0 h and 4 h. Concentrations of prolactin were correlated in pairs of milk or blood samples from the same ewe and in plasma and milk of ewes in group 2 but not in group 1. Prolactin in milk increased between 0 h and 4 h in groups 1 and 2. Although milk lactose and prolactin concentrations differed among hourly samples, their average was similar to that of milk accumulated in the contralateral side for 4 h (group 1). Variations among ewes in progesterone of plasma indicated luteal activity during autumn and none during summer. Prolactin was unchanged in milk stored at -23 C for 30 days. The hour-0 milk-sampling technique was satisfactory to compare among individuals the concentrations of prolactin, total protein, or somatic cells in milk but not percentage fat and lactose, or milk yield due to variable time from last suckling to milking at hour 0.

Animals↗
PubMed1992

Collection of fore and hind milk from the sow and the changes in milk composition during suckling.

A new sampling method for the collection of fore and hind milk from the sow has been developed which resembles normal milk removal by the piglet, yet overcomes the difficulties of collecting milk that is available for only a short time (10-20 s) at each let-down. Samples of hind milk were collected immediately after the completion of a successful sucking, while the fore milk was collected at the beginning of the next natural let-down. Modification of existing assays for fat, protein and lactose was required to provide rapid analysis of the small volumes (less than 0.5 ml) of milk collected using this procedure, and these methods were validated by comparison with reference methods. Total solids and the concentration of fat in whole milk, and protein and lactose in skim milk, were measured in fore and hind milk collected from 4, 20, 12 and 12 sows respectively, 6-11 d post partum. For fore milk, the results (mean +/- SD (n)) were: total solids, 199.9 +/- 9.9 g/l (8); fat, 96.7 +/- 13.9 g/l (41), protein, 47.7 +/- 4.5 g/l (27) and lactose, 58.3 +/- 4.0 g/l (27). In hind milk, there was a significant increase in the concentration of fat (15.3 g/l, P less than 0.001, n = 41) which was reflected by a significant increase in total solids (14.7 g/l, P less than 0.001, n = 8) and calculated energy (511 kJ/l, P less than 0.001, n = 27), but there was no significant difference in the concentration of either protein or lactose. This increase in milk fat during milk let-down is in contrast to the results of most previous studies in the sow and is discussed in terms of the possible mechanisms that may cause the concentration of fat to increase as milk is removed from the mammary gland.

Animals↗
PubMed1979

Bacteriostasis of Escherichia coli by milk. III. The activity and stability of early, transitional and mature human milk collected locally.

Milk from 150 local mothers has been assayed for bacteriostatic activity for milk-sensitive and milk-resistant indicator strains of Escherichia coli. Activity is greatest in colostrum which is active directly against all strains of E. coli. One week after delivery of the baby, milk is active against the milk-sensitive strain and becomes active against the milk-resistant strain in the presence of physiological amounts of bicarbonate and iron-binding protein. This activity decreases within 2--4 days on keeping milk unheated at 4 degrees C but is preserved for at least 4 months and often up to 2 years in milk heated to 56 degrees C then stored at 4 degrees C or in milk frozen, unheated, at -28 degrees C provided it is not repeatedly thawed and frozen. Later lactation milks are usually indistinguishable in activity from 1-week post-partum milk but may be less stable on storage particularly if frozen. Lyophyilization in vacuo preserves activity of early-lactation milk for at least 6 months. Heating milk to above 65 degrees C causes a progressive loss of activity which can be partially restored by adding bicarbonate and iron-binding protein. Iron abolishes the activity of milk and reduces that of colostrum.

Bicarbonates↗
PubMed2026

CanDo (Canadian Donor Milk) randomised controlled trial: pasteurised human donor milk supplementation in the well-baby unit - protocol.

INTRODUCTION: Mother's milk is the gold standard for feeding newborns. Despite lactation support while in hospital, supplementation rates remain high in Canadian well-baby units at 35-50%. When supplementation is needed, the choice between formula milk and pasteurised human donor milk (donor milk) remains uncertain with a lack of clinical trials to inform this practice. This study aims to compare the effect of supplementing mother's milk with donor milk versus formula in infants at higher risk for supplementation (infants of diabetic mothers, infants born small for gestational age or with a birth weight less than 2.5 kg and late preterm infants born between 350/7 and 366/7 weeks gestation). METHODS AND ANALYSIS: This is an ongoing, open-label, single-centre, randomised controlled trial conducted at Mount Sinai Hospital, Toronto, Canada. A total of 112 infants (56 per group) will be randomised to receive donor milk or infant formula as a supplement to mother's milk during their initial hospital stay, when supplementation is deemed necessary by the family and/or healthcare team. The primary outcome is exclusive human milk feeding at 4 months of age. Secondary outcomes include any or exclusive human milk feeding at 1, 2 and 3 months; infant growth and health indicators and breastfeeding self-efficacy. Exploratory outcomes encompass infant temperament; parental mental health (assessed using the State-Trait Anxiety Inventory and Edinburgh Postnatal Depression Scale); milk cortisol concentrations; and informal milk sharing comparing donor milk and formula supplementation. Follow-up includes monthly telephone assessments and a virtual or in-person visit at 4 months post partum. Data will be analysed using intention-to-treat principles. ETHICS AND DISSEMINATION: The CanDo trial has received ethics approval from the Mount Sinai Hospital Research Ethics Board and the University of Toronto. Results will be disseminated through peer-reviewed journals, conference presentations and stakeholder engagement with hospital and public health decision-makers. Findings will address a critical evidence gap regarding the use of donor milk supplementation in well-baby units and may inform future clinical practice and policy in newborn feeding. TRIAL REGISTRATION NUMBER: NCT06315127.

Humans↗
PubMed1978

Effects of processing milk on concentrations of glucocorticoids in milk.

Concentrations of glucocorticoids were measured by protein binding in milk subjected to various processing methods. Raw whole milk was collected once per week for 3 wk from bulk milk tanks of each of 10 farms. Nine combinations of processing were tested: 1) none, 2) high-temperature short-time pasteurization of whole milk, 3) high-temperature short-time pasteurization and homogenization of whole milk, 4) bulk pasteurization of whole milk, 5) bulk pasteurization and homogenization of whole milk, 6) high-temperature short-time pasteurization of skim milk, 7) high-temperature short-time pasteurization and homogenization of skim milk, 8) bulk pasteurization of skim milk, and 9) bulk pasteurization and homogenization of skim milk. Mean concentrations of total glucocorticoids ranged from .46 to .65 ng/ml and were not different among either processing methods or whole versus skim milk classifications. No correlations were positive between percentage of fat and concentration of glucocorticoids in whole milk (-.22) or skim milk(-.09).

Animals↗
PubMed1976

[Lipic content and fatty acid pattern in human milk and cow's milk (author's transl)].

The lipid content and the fatty acid pattern in human colostrum, transitional and mature molk and in pasteurised cow's milk and in "Vorzugsmilch" (special untreated milk) were investigated. The analyses were done in pooled daily milk of 15-20 women to archieve representative mean values for human milk. The lipid content amounted to 1.87 g/100 ml in human colostrum, 2.82 g/100 ml in transitional mild and 3.45 g/100 ml in mature human milk. The increase of lipid content during lactation is attributed to maturation of the milk and is not influenced by maternal diet. During maturation of human milk decreases the portion of the unsaturated fatty acids from 57 to 53%, the portion of saturated fatty acids increases accordingly from 43 to 47%. The decrease of the unsaturated fatty acids is mainly due to the decrease of oleic acid while the portion of linoleic acid increases from 10.8 to 12.0%. In the same duration the linoleic acid portion of the energy content of human milk increases there with from 3.3 keal % in colostrum to 5.6 kcal % in mature human milk. Lipid content and fatty acid pattern of pasteurised cow's milk and "Vorzugsmilch" were compared with the corresponding values in human milk. The importance of the differences in lipid content and fatty acid pattern of human milk and cow's milk for the nutrition of healthy young infants is discussed.

Animals↗
PubMed1992

Studies on the excretion of diazepam and nordazepam into milk for the prediction of milk-to-plasma drug concentration ratios.

The influence of varying protein and fat content in milk of New Zealand White rabbits on the milk-to-plasma drug concentration (M/P) ratio of diazepam was studied. At various time points after littering, a bolus dose (1.5 mg/kg) followed by a 26-hr infusion (1.8 mg/h) of diazepam was administered to freely moving rabbits via a jugular vein catheter. Milk and blood samples were collected to allow characterization of milk composition and quantitative determination of diazepam and nordazepam in milk and plasma. At steady state diazepam showed M/P ratios between 3.7 and 9.5, whereas nordazepam showed ratios between 2.1 and 4.3, respectively. The relative importance of milk protein binding and milk-fat partitioning for the excretion of a drug into milk depended on the drug's affinity to milk fat. A stepwise multiple regression analysis suggested that observed M/P ratios of diazepam could be explained by considering the fat content of milk alone. Nordazepam with a lower solubility in milk fat showed M/P ratios which could be best explained by considering protein and fat concentrations together. Using the data from the infusion studies, two recently published diffusional models to predict M/P ratios were evaluated. Neither model could accurately predict the M/P ratios of diazepam and nordazepam observed in rabbits. However, after extending the model described by Atkinson and Begg to take the actually measured partitioning between skim milk and milk fat into account, a great improvement in the predictive power for observed M/P ratios occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Bone mineral metabolism in full-term infants fed human milk, cow milk-based, and soy-based formulas.

OBJECTIVE: To study the hypothesis that ingestion of a modified soy-based formula with an improved mineral suspension system may result in bone mineral content similar to that observed in infants fed human milk or cow milk-based formulas. DESIGN: Prospective, self-selected group of infants fed human milk randomized between the two formula-fed groups. SETTING: University-based hospital nursery and follow-up. PARTICIPANTS: Fifty-six normal, healthy, full-term infants, free of major malformations or disorders, including 17 infants fed human milk, 19 infants fed a cow milk-based formula, and 20 infants fed a soy protein formula were followed up to 6 months' postnatal age. The soy-based formula studied was modified to improve the suspendability of the minerals. INTERVENTIONS: Infants were fed human milk or the study formula for the first 4 months, at which time beikost was permitted. Infants fed human milk received vitamin supplementation to provide 400 IU of vitamin D per day. MEASUREMENTS: Anthropometric variables, serum calcium, magnesium, phosphorus, alkaline phosphatase, and parathyroid hormone levels were measured at enrollment, and at 8, 16, and 24 to 26 weeks' postnatal age. Bone mineral content at the distal third radius site was measured with single photon absorptiometry at these times. Growth in the infants did not differ significantly among the groups. There was no significant difference in serum calcium, magnesium, alkaline phosphatase, or parathyroid hormone concentrations among the infants during the study. Serum phosphorus was significantly lower at 8 weeks in the group fed human milk than in that fed the cow milk-based formula. Bone mineral content at 16 and 24 to 26 weeks was higher in the group fed the soy-based formula than in that fed human milk, and bone width was also higher at 16 weeks in the infants fed the soy-based formula. CONCLUSIONS: Improving the suspendability of the mineral system in the soy formula results in bone mineralization in infants fed the soy-based formula similar to that measured in infants fed human milk and cow milk-based formula. We suggest that the suspendability of the minerals used is an important variable in the interpretation of the effect of feedings on the bone mineral status of infants.

Animals↗
PubMed1978

Relative zinc availability in human breast milk, infant formulas, and cow's milk.

The concentration and bioavailability of zinc was analyzed in 10 varieties of milk. The concentration of zinc averaged 4.1 microgram/ml in unprocessed (raw) cow's milk; fortified infant formulas contained about 3 to 5 microgram Zn/ml; human breast milk and processed cow's milk contained approximately 2 microgram Zn/ml; sweetened condensed milk contained 1.3 microgram Zn/ml, and reconstituted nonfat dry milk contained 0.4 microgram Zn/ml. The mean values for zinc bioavailability to rats were as follows: sweetened condensed milk = 66%; human breast milk 59.2%, processed cow's milk = 43.7 to 50.9%; unprocessed (raw) cow's milk = 42%; nonfat dry milk = 41.2%, and infant formulas = 26.8 to 39.5%. Assuming similar absorption of zinc in rats and humans, our experimental results provide some guidelines for estimating the quantity of zinc that would actually be absorbed from various types of milk.

Animals↗